The difference is that the former does not threaten the security of the great powers, whereas the latter undermines it in the most dangerous way possible. — Tzeentch

I wouldn't necessarily agree, as Israel officially adopting mass terrorism is going to motivate similar attacks on both Israel and the US as well as normalize the practice generally speaking which effects also everyone, and likewise eroding the US credibility and diplomatic position is a threat to US interests and thus security while also threatening to drag the US into a disfavour able war, but even assuming what you say is true and the former are of no concern to the US or the other great powers, can the great powers do anything about it?

Simply being a great power doesn't magically make your will happen, in this case even with respect to your own colony that you've setup, funded, nurtured and shielded. We are in an unusual situation where a colony has effectively taken control of the foreign policy of the empire from which it comes.

If not completely, clearly enough to carry out a genocide in broad daylight and boast about the fact, likewise praise rapists and blowup embassies and assassinate high officials left and right. None of this benefits US security since all of these norms are bedrock parts of the "rules based order" US officials keep going on about and some of the rules (like not being explicitly genocidal, explicitly pro raping prisoners, and not blowing up embassies) the US even follows itself (assassination being the one policy US also carries out with the expectation no one does it to them, but even there the US is clearly far more restrained than Israel)!!

Israel is simply not effectively constrained by the great powers at the moment so what the great powers want is not a determining factor in this situation.

On top of all of that, it's also debatable the extent to which US elites are actually against Israel nuking Iran. There's clearly a strong faction of US elites that wants war with Iran while, as @ssu notes, never elaborating how exactly a war with Iran would unfold; perhaps their idea is that Israel will nuke Iran all while being protected by the US from retaliation. They clearly don't have in mind a full-scale invasion, occupation and building up a liberal democracy over several decades only to be defeated by the Taliban again, yet they talk about war with Iran a lot so they must have some sort of idea of how that would actually go. If it is as obvious that Iran cannot be invaded conventionally as everyone familiar with the matter seems to believe, it would seem equally obvious that nuclear weapons is the only recourse that changes that equation.

Nuclear proliferation is one of the only topics the great powers have generally been in agreement over. They realise the consequences to global security, including their own, if the nuclear genie is let out of the bottle. — Tzeentch

Agreed, but Israel already has nuclear weapons and the great powers were unable to prevent that nor would they be able to prevent Israel using those nuclear weapons.

What would ensue after an unprovoked nuclear attack is a mad scramble where virtually every nation on the planet will be trying to get their hands on nuclear deterrents and anti-ballistic missile defenses of their own. — Tzeentch

Agreed. Again, doesn't stop Israel from using nuclear weapons. One may assume that proliferation would lead to Israel eventually being nuked, but they may (whether they are delusional or not about it) believe that preemptively nuking Iran enough will deter that from happening. The US nuked Japan and has yet to be nuked in return; that maybe their model.

At that point, the great powers would likely do everything in their power to crack down on the culprit in an attempt to cool global fear. — Tzeentch

Again, how? And also maybe Israel elites believe, rightly or wrongly, that the US simply won't do any such thing.

For, Israel is a tiny country and so it simply doesn't require that much inputs to keep afloat.

If all the "hippy liberals" and "startup bros" have mostly already left Israel, perhaps those that remain in Israel have little problem with the idea of becoming an insular rogue state exactly as you describe, confident that the US will continue to supply them with whatever they actually need. After the nuking, they'll be able to simply occupy the land they want, kill or displace whoever they want, and after that (at least believe now) they'll be left alone.

Now, the analysis I provide is not meant as a prediction, that this is the most likely outcome. My point is that this is where the trend is going and we'd need a solid theory based on prior knowledge, i.e. evidence, to predict the trend will change before nuclear weapons use.

It could very well be Israel is "escalating to deescalate" and is repeating their former pattern of disproportionate retaliation just with a bit extra "oomph" this time. That their enemies will have "learned a lesson" and will think twice about messing with them again.

It's also possible that the plan is to provoke a conventional war between Iran and the US and that they have some plan how that will go, or anyways think it's a good idea even without an actual plan.

It's likewise possible Israel is simply conquering more territory and once they have it they feel they can defend it at a sustainable cost.

Another possibility is recent events are driven mostly by Israeli internal politics to solidify Netanyahu's hold on power, trying to push the limit to distract from Israeli internal problems while satisfying the population with perceived victory, without intending to go more extreme than the current policies, and the long term security implications are not really a factor (of making more enemies, of losing enormous international sympathy, of not being unable to hold territory in Lebanon assuming that's the case, of angering the entire Muslim world for generations and so on).

So, there are many possibilities, none of which we have much data to exclude nor support above the others, but my basic point is that nuking Iran is one such possibility and directly in line with the current trajectory of going rogue on everything else and detonating taboo after taboo in an accelerating fashion.

In terms of reasoning structure, we need actual evidence (prior knowledge) upon which to base predicting a trajectory in the data will suddenly change.

I gave the analogy of the water. Another analogy would be simply throwing a ball. We know how to predict the trajectory of projectiles and in order to predict a sudden change in the data we'd need actual knowledge of something that's going to affect the balls path. Obviously if we can literally see a building in front of the ball, or we know the ball was thrown at ground level and there's no giant cliffs around, or we know someone is aiming to shoot the ball with a high precision anti-ball system, or someone there to catch the ball, etc. then that's excellent knowledge in which to predict the ball will not simply continue on an expected high-school physics trajectory (speed, gravity, air resistance etc.; which, even that presumes knowledge of the ball being thrown somewhere close to the surface of the earth and not on the moon or elsewhere in space; even the simple prediction "the ball will be stoped by something at some point" requires prior knowledge about the situation).

Now, before Israel blew past all these taboos we did have the prior knowledge that Israel did place limits to its violent actions, so if we were having this conversation a year ago, or perhaps even a few months ago or even literally weeks ago, the "restraint theory" (either self-restraint or then the great powers as you propose above) would have had significant weight. I definitely didn't predict where we are now a year ago; my expectation being things would be bloody but ultimately return to the status quo (as that is what has always happened before).

And certainly the theory that despite appearance we are not actually outside the previous pattern of violence and Israeli war planners fully expect everything to "go back to normal" can be argued. It certainly feels like "things are different this time" but perhaps that is only a feeling and in another year tourists will be back on the beaches, tech bros raving in their techno parties in Tel Aviv, Palestinians still in concentration camps with little international concern for their well being dealing with the raping and murdering as best they can, tensions with Iran exactly as the same as they usually are and the spice continuing to flow from the Middle-East as it usually does. That is possible.

However, when Netanyahu says Iran will be free sooner than expected he may not be referring to the freedom that the US generously brings to a country after a large scale invasion and decades of occupation and tutelage, and he may not just be talking bluster because that's what leaders in wars do, but rather he maybe referring to freeing Iranian spirits from their bodies in by cleansing light of the nuclear flame.

Nuking Iranian leadership and population centres is the only practical interpretation of Netanyahu's words, that is unless I'm missing some other way of exporting freedom to Iran.

Also, notice that in the time we are discussing this a new data point is created by Israel which tracks the nuke Iran trajectory: "warning" the Iranian people themselves so they can say "we warned them and they didn't listen" after everything is made "different" than it was before.

I already watched this video (I think you posted it already). I find Gideon’s argument, from premises to conclusions, enough plausible in light of available evidences and universal humanitarian concerns. However, I don’t find it particularly enlightening from a geopolitical and historical perspective (I elaborated on this in several previous posts, not sure if you read them).
So what I would really like to understand is: is it geopolitical and historical reasoning that is blind to universal humanitarian concerns or is it universal humanitarian concerns that are blind to geopolitical and historical reasoning? I think the second is way more likely, hence the spectacular and endless frustration of the universal human rights activists.